Photonic crystal all-optical self-or-transformation logic gate

ABSTRACT

A photonic crystal (PhC) all-optical self-OR-transformation logic gate, which comprises an optical-switch unit (OSU), a PhC structure unit, a reference-light source, a memory or delayer and a D-type flip-flop (DFF); an input port of a delayer is connected with a logic-signal X, and an output port of said delayer is connected with the logic-signal-input port of said OSU; a reference light is connected to the reference-light-input port of said OSU; two intermediate-signal-output ports of said OSU are respectively connected with the two intermediate-signal-input port of said PhC-structure unit; a clock-signal CP is connected to the clock-signal-CP-input port of said OSU and the second clock-signal-input port of said DFF; the signal-output port of said PhC-structure unit is connected with the D-signal input port of said DFF. The structure of the present invention is compact in structure, strong in anti-interference capability and ease in integration with other optical-logic elements.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation application of Application No.PCT/CN2015/097850 filed on Dec. 18, 2015, which claims priority toChinese Application No. 201410799695.4 filed on Dec. 19, 2014, theentire contents of which are hereby incorporated by reference.

FIELD OF THE INVENTION

The present invention relates to two-dimensional (2D) photonic crystal(PhC) optical self-OR-transformation logic gates.

BACKGROUND OF THE INVENTION

In 1987, the concept of PhC was proposed separately by E. Yablonovitchfrom United States Bell Labs who discussed how to suppress spontaneousradiation and by S. Johnfrom Princeton University who made discussionsabout photonic localization. A PhC is a material structure in whichdielectric materials are arranged periodically in space, and is usuallyan artificial crystal consisting of two or more materials havingdifferent dielectric constants.

With the emergence of and in-depth research on PhC, people can controlthe motion of photons in a PhC material more flexibly and effectively.In combination with traditional semiconductor processes and integratedcircuit technologies, design and manufacture of PhCs and devices thereofhave continually and rapidly marched towards all-optical processing, andthe PhC has become a breakthrough for photonic integration. In December1999, the PhC was recognized by the American influential magazineScience as one of the top-ten scientific advances in 1999, and thereforehas become a hot topic in today's scientific research field.

An all-optical-logic device mainly includes an optical amplifier-basedlogic device, a non-linear loop mirror logic device, a Sagnacinterference-type logic device, a ring-cavity logic device, amulti-mode-interference logic device, an optical-waveguide-coupled logicdevice, a photoisomerized logic device, a polarization-switchoptical-logic device, a transmission-grating optical-logic device, etc.These optical-logic devices have the common shortcoming of large size indeveloping large-scale integrated optical circuits. With the improvementof science and technology in recent years, people have also doneresearch and developed quantum-optical-logic devices,nanomaterial-optical-logic devices and PhC optical-logic devices, whichall conform to the dimensional requirement of large-scale integratedoptical circuits. For modern manufacturing processes, however, thequantum-optical-logic devices and the nanomaterial-optical-logic devicesare very difficult to be manufactured, whereas the PhC optical-logicdevices have competitive advantages in terms of manufacturing process.

In recent years, PhC logic devices have become a hot area of researchdrawing widespread attentions, and it is highly likely for them toreplace the current widely-applied electronic-logic devices in the nearfuture. The PhC logic device can directly realize all-optical-logicfunctions, such as “AND”, “OR”, “NOT” and the like, and is a core devicefor realizing all-optical computing. In the process of realizingall-optical computing, PhC logical function devices based on “AND”,“OR”, “NOT”, “XOR” and the like have been successfully designed andstudied, and various complex logic components are still needed forachieving the goal of all-optical computing.

SUMMARY OF THE INVENTION

The present invention is aimed at overcoming the defects of the priorart and providing a PhC all-optical self-OR-transformation logic gatecompact in structure, strong in anti-interference capability and easy tointegrate with other optical-logic elements.

The technical proposal adopted by the invention to solve the technicalproblem is as follows:

A PhC all-optical self-OR-transformation logic gate of the presentinvention includes an optical switch unit (OSU), a PhC-structure unit, areference-light source, a memory or delayer and a D-type flip-flop(DFF);an input port of a delayer is connected with a logic-signal X, and anoutput port of the delayer is connected with the logic-signal-input portof the OSU; a reference-light E is connected with thereference-light-input port of the OSU; two intermediate-signal-outputports of the OSU are respectively connected with the twointermediate-signal-input ports of the PhC-structure unit; aclock-signal CP is input through the input port of a two-branchwaveguide, one port of the two-branch waveguide is connected with theclock-signal-CP-input port of the OSU, and another port of thetwo-branch waveguide is connected with the clock-signal-input port ofthe DFF; the signal-output port of the PhC-structure unit is connectedwith the D-signal-input port of the DFF.

The OSU is a 2×2 optical-selector switch; the OSU includes aclock-signal-CP-input port, a logic-signal-input port, areference-light-input port and two intermediate-signal-output ports; thetwo intermediate-signal-output ports are respectively a firstintermediate-signal-output port and a second intermediate-signal-outputport.

The PhC-structure unit is a 2D-PhC cross-waveguide nonlinear cavity; thePhC-structure unit is 2D-PhC cross-waveguide four-port network formed byhigh-refractive-index dielectric pillars, a left port of the four-portnetwork is a first intermediate-signal-input port, a lower port is asecond intermediate-signal-input port, an upper port is a signal-outputport, and a right port is an idle port; two mutually-orthogonal quasi-1DPhC structures are placed in two waveguide directions crossed at acenter of a cross-waveguide; a dielectric pillar is arranged in a middleof the cross-waveguide, the dielectric pillar is made of a nonlinearmaterial, the cross section of the dielectric pillar is square,polygonal, circular or oval; the dielectric constant of a rectangularlinear pillar clinging to the central nonlinear pillar and close to thesignal-output port is equal to that of the central nonlinear-pillarunder low-light-power conditions; the quasi-1DPhC structures and thedielectric pillar constitute a waveguide defect cavity.

The memory or delayer 04 includes an input port and an output port; theoutput signal of the delayer has T/2 delay relative to the input signalthereof, where T is a clock period.

The memory or delayer provides the one of T/2 delay.

The DFF includes a clock-signal-input port, a D-signal-input port and asystem-output port; the input signal of the D-signal-input port of theDFF is equal to the output signal of the output port of thePhC-structure unit.

The PhC structure is a (2k+1)×(2k+1) array structure, where k is aninteger more than or equal to 3.

The cross section of the high-refractive-index dielectric pillar of the2D-PhC is circular, oval, triangular or polygonal.

A background filling material for the 2D-PhC is air or a differentlow-refractive-index medium with the refractive index less than 1.4

The cross section of the dielectric pillar in the quasi-1D PhC isrectangular, polygonal, circular or oval, and the refractive index ofthe dielectric pillar is 3.4 or a different value more than 2.

Compared with the prior art, the present invention has the followingadvantages:

1. Compact in structure, and ease of manufacture;

2. Strong anti-interference capability, and ease of integration withother optical-logic elements; and

3. High contrast of high and low logic outputs, and fast operation.

These and other objects and advantages of the present invention willbecome readily apparent to those skilled in the art upon reading thefollowing detailed description and claims and by referring to theaccompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a structural schematic diagram of a PhC all-opticalself-OR-transformation logic gate of the present invention;

In FIG. 1, the indications are: OSU 01, logic-signal-input port 11,reference-light-input port 12, first intermediate-signal-output port 13,second intermediate-signal-output port 14, PhC-structure unit 02, firstintermediate-signal-input port 21, second intermediate-signal-input port22, idle port 23, signal-output port 24, circularhigh-refractive-indexlinear-dielectric pillar 25, first rectangular high-refractive-indexlinear-dielectricpillar 26, second rectangular high-refractive-indexlinear-dielectric pillar 27, central nonlinear-dielectric pillar 28,reference-light 03, reference-light E, delayer or memory 04,logic-signal X, clock-signal CP, DFF 05, clock-signal-input port 51,D-signal-input port 52, system-output port 53.

FIG. 2 is a waveform diagram of the basic logic functions of aPhC-structure unit of the present invention shown in FIG. 1 for thelattice constant d of 1 μm and the operating wavelength of 2.976 μm;

FIG. 3 is a waveform diagram of the logic-signal self-OR-transformationlogic function of the PhC all-optical self-OR logic gate of the presentinvention for the lattice constant d of 1 μm and the operatingwavelength of 2.976 μm;

FIG. 4 is a truth table of the logic functions of a 2D-PhCcross-waveguide nonlinear cavity shown in FIG. 1.

The present invention is more specifically described in the followingparagraphs by reference to the drawings attached only by way of example.

DETAILED DESCRIPTION OF THE EMBODIMENTS

The terms a or an, as used herein, are defined as one or more than one,the term plurality, as used herein, is defined as two or more than two,and the term another, as used herein, is defined as at least a second ormore.

As shown in FIG. 1, the PhC all-optical self-OR-transformation logicgate of the present invention includes an OSU 01, a PhC-structure unit02, a reference-light source 03, a memory or delayer 04 and a DFF 05;the OSU 01 is a 2×2 optical-selector switch controlled by a clock-signalCP, used for controlling and selecting a logic-signal for outputting asthe logic input of next stage of the PhC-structural unit; and includes aclock-signal-CP-input port, a logic-signal-input port, areference-light-input port and two intermediate-signal-output ports; andthe two intermediate-signal-output ports are respectively a firstintermediate-signal-output port and a second intermediate-signal-outputport; the memory or delayer 04 includes an input port and an outputport; the memory or delayer provides the one of T/2 delay, thelogic-signal X is input from the input port of the delayer 04, and theoutput port of the delayer outputs a delay-signal X(t−T/2) having T/2delay and is connected with the logic-signal-input port 11 of the OSU;the memory or delayer is arranged between the delay-signal-input port ofthe system and the OSU, the delayer is used for delaying the inputsignal, the output signal of the delayer has a delay of T/2 relative tothe input signal thereof, where T is a clock period; and areference-light source outputs reference-light E, E=1, which is furtherprojected to the reference-light-input port of an optical-selectorswitch; the first intermediate-signal-input port 21 of the PhC-structureunit 02 is connected with the first intermediate-signal-output port 13of the optical-selector switch, the second intermediate-signal-inputport 22 of the PhC-structure unit 02 is connected with the secondintermediate-signal-output port 14 of the optical-selector switch; theDFF 05 includes a clock-signal-input port, a D-signal-input port and asystem-output port; a clock-signal CP is input through the input port ofa two-branch waveguide, one port of the two-branch waveguide isconnected with the clock-signal-CP-input port of the optical-selectorswitch 01, and another port of the two-branch waveguide is connectedwith the clock-signal-input port 51 of the DFF 05; the signal-outputport 24 of the PhC-structure unit 02 is connected with theD-signal-input port 52 of the PhC DFF 05, i.e., the input signal 52 atthe D-signal-input port 52 of the DFF 05 is equal to the output signalat the output port 24 of the PhC-structure unit 02; thesystem-signal-output port 53 of the DFF 05 is the system-output port ofthe PhC all-optical self-OR-transformation logic gate of the presentinvention;

the PhC-structure unit 02 is a 2D-PhC cross-waveguide nonlinear cavityand is arranged behind the OSU, the background filling material for the2D-PhC is air or a different low-refractive-index medium with arefractive index less than 1.4, the cross section of thehigh-refractive-index dielectric pillar of the 2D-PhC is circular, oval,triangular or polygonal, the 2D-PhC cross-waveguide nonlinear cavity isa 2D-PhC cross-waveguide four-port network formed byhigh-refractive-index dielectric pillars, the four-port network has afour-port PhC structure, the left port is a firstintermediate-signal-input port, the lower port is a secondintermediate-signal-input port, the upper port is a signal-output port,and the right port is an idle port; two mutually-orthogonal quasi-1D PhCstructures are placed in two waveguide directions crossed at the centerof a cross-waveguide, the cross section of the dielectric pillar in thequasi-1D PhC is rectangular, polygonal, circular or oval, the refractiveindex of the dielectric pillar is 3.4 or a different value more than 2,a dielectric pillar is arranged in the middle of the cross-waveguide,the dielectric pillar is made of a nonlinear material, the cross sectionof the dielectric pillar is square, circular, oval, triangular orpolygonal, and the quasi-1D PhC structures and the dielectric pillarconstitute a waveguide defect cavity. The lattice constant of the 2D-PhCarray is d, and the array number is 11×11; the circularhigh-refractive-index linear-dielectric pillar 25 is made of a silicon(Si) material, and has a refractive index of 3.4 and a radius of 0.18 d;the first rectangular high-refractive-index linear-dielectric pillar 26has a refractive index of 3.4, long sides of 0.613 d and short sides of0.162 d; the second rectangular high-refractive-index linear-dielectricpillar 27 has a dielectric constant being the same as that of anonlinear-dielectric pillar under low-light-power conditions, and has adimension equal to that of the first rectangular high-refractive-indexlinear-dielectric pillar 26; and the central square nonlinear-dielectricpillar 28 is made of a Kerr-type nonlinear material, and has a sidelength of 1.5 d, a dielectric constant of 7.9 under low-light-powerconditions and a third-order nonlinear coefficient of 1.33×10² μm²/V².Twelve rectangular high linear-dielectric pillars and one squarenonlinear-dielectric pillar are arranged in the center of the 2D-PhCcross-waveguide nonlinear cavity in the form of a quasi-1D PhC alonglongitudinal and transverse waveguide directions, the centralnonlinear-dielectric pillar clings to the four adjacent rectangularlinear-dielectric pillars and the distance there between is 0, every twoadjacent rectangular linear-dielectric pillars are spaced 0.2668 d fromeach other, and the dielectric constant of a rectangular linear-pillarclinging to the central nonlinear-pillar and close to the signal-outputport is equal to that of the central nonlinear-pillar underlow-light-power conditions.

The present invention can realize a self-OR-transformation logic gatefunction and a multistep-delay self-OR-transformation logic gatefunction of all-optical-logic-signals under the cooperation of unitdevices such as the optical switch, based on the photonic bandgap (PBG)characteristic, quasi-1D PhC defect state, tunneling effect and opticalKerr nonlinear effect of the 2D-PhC cross-waveguide nonlinear cavityshown by PhC-structure unit 02 in FIG. 1. Introduced first is the basicprinciple of the PhC nonlinear cavity in the present invention: a 2D-PhCprovides a PBG with a certain bandwidth, a light wave with itswavelength falling into this bandgap can be propagated in an opticalpath designed inside the PhC, and the operating wavelength of the deviceis thus set to a certain wavelength in the PBG; the quasi-1D PhCstructure arranged in the center of the cross-waveguide and thenonlinear effect of the central nonlinear-dielectric pillar togetherprovide a defect state mode, which, as the input-light wave reaches acertain light intensity, shifts to the operating frequency of thesystem, so that the structure produces the tunneling effect and signalsare output from the output port 24. For the lattice constant d of 1 μmand the operating wavelength of 2.976 μm, referring to the 2D-PhCcross-waveguide nonlinear cavity shown by 02 of FIG. 1, and for a signalA input from the port 21 and a signal B input from the port 22 as shownby the upper two diagrams in FIG. 2, a logic output waveform diagram ofthe 2D-PhC cross-waveguide nonlinear cavity of the present invention canbe obtained, as displayed by the waveforms at the lower part in FIG. 2.A logic operation truth table of the structure shown in FIG. 4 can beobtained according to the logic operation characteristic shown in FIG.2. In FIG. 4, C is current state Q^(n), and Y is signal-output of theoutput port 24—the next state Q^(n+1). A logic expression of thestructure can be obtained according to the truth table.Y=AB+BC  (1)That isQ ^(n+1) =AB+BQ ^(n)  (2)

According to the basic logic operation characteristic of the above2D-PhC cross-waveguide nonlinear cavity, the logic output of theprevious step serves as a logic in put to the structure itself torealize logic functions.

As shown in FIG. 1, for CP=0, the optical-selector switch turns theinput signal X(t−T/2) of the T/2 delay at the logic-signal-input port 11to the second intermediate-signal-output port 14 of the optical-selectorswitch, and the input signal X(t−T/2) is further projected to the secondintermediate-signal-input port 22 of the PhC-structure unit 02, thus theinput signal of the second intermediate-signal-input port 22 of thePhC-structure unit 02 is equal to the input signal X(t−T/2) at thelogic-signal-input port 11; simultaneously, the optical-selector switchturns the reference-light E at the reference-light-input port 12 to thefirst intermediate-signal-output port 13 of the OSU, and thereference-light E is further projected to the firstintermediate-signal-input port 21 of the PhC-structure unit 02, thus theinput signal of the first intermediate-signal-input port 21 of thePhC-structure unit 02 is equal to the reference-light E at thereference-light-input port 12.

For CP=1, the optical-selector switch turns the input signal X(t−T/2+1)at the logic-signal-input port 11 to the thirdintermediate-signal-output port 13 of the optical-selector switch, andthe input signal X(t−T/2+1) is further projected to the firstintermediate-signal-input port 21 of the PhC-structure unit 02; thus theinput signal at the first intermediate-signal-input port 21 of thePhC-structure unit 02 is equal to the input-signal X(t−T/2+1) at thelogic-signal-input port 11; simultaneously, the optical-selector switchturns the reference-light E at the reference-light-input port 12 to thesecond intermediate-signal-output port 14 of the optical-selectorswitch, and the reference-light E is further projected to the secondintermediate-signal-input port 22 of the PhC-structure unit 02, thus theinput signal of the second intermediate-signal-input port 22 of thePhC-structure unit 02 is equal to the reference-light E of thereference-light-input port 12.

The PhC structure of the device in the present invention can be of a(2k+1)×(2k+1) array structure, where k is an integer more than or equalto 3. Design and simulation results will be provided below in anembodiment given in combination with the accompanying drawings, whereinthe embodiment is exemplified by an 11×11 array structure and a latticeconstant d of 1 μm.

In formula (2), suppose A=1, leading toQ ^(n+1) =B  (3)In formula (2), suppose B=1, leading toQ ^(n+1) =A+Q ^(n)  (4)

Thus, the signal X is input to the second intermediate-signal-input port22 of a PhC-structural unit 02 at the moment t_(n), i.e., B=X(t_(n));simultaneously, supposing that the input signal A at the port 21 isequal to 1, the logic-input signal X(t_(n)) at the moment t_(n) isstored in an optical circuit; then, at the moment t_(n+1), the signalX(t_(n+1)) is input to the first intermediate-signal-input port of 21 inthe PhC-structural unit 02, i.e., the logic-input signal A at the firstintermediate-signal-input port 21 at the moment is equal to X(t_(n+1)),and simultaneously, supposing that the logic-input-signal B of thesecond intermediate-signal-input port 22 is equal to 1, it can beobtained from formula (2).Q ^(n+1) =X(t _(n+1))+X(t _(n))  (5)

Hence, a CP signal, an optical switch and a reference-light source needto be introduced into the system; for CP=0, the optical switch 01projects the signal X to the second intermediate-signal-input port 22,and simultaneously projects the signal “1” to the firstintermediate-signal-input port 21; and for CP=1, the optical switch 01projects the signal X to the first intermediate-signal-input port 21,and simultaneously projects the signal “1” to the secondintermediate-signal-input port 22. Because the input quantity oflogic-signals within a clock period is unchanged, a delayer havingT/2delay needs to be introduced into the signal-input port of the systemto realize an OR-transformation function of logic-signals of adjacentclock cycles.

The optical-selector switch operates as follows under the control of aclock-signal CP:

At a moment t_(n), CP is made equal to 0, the optical-selector switchtransmits the signal X(t_(n)−T/2) of the logic-signal-input port 11 tothe second intermediate-signal-output port 14, and the delay signalX(t_(n)−T/2) is further projected to the secondintermediate-signal-input port 22 of the PhC-structure unit 02; andsimultaneously, the optical-selector switch transmits thereference-light E at the reference-light-input port 12 to the firstintermediate-signal-output port 13, and the reference-light E is furtherprojected to the first intermediate-signal-input port 21 of thePhC-structure unit 02; The output of the port 24 at this moment can beobtained from the expression (2):Q ^(n+1) =X(t−T/2)  (6)

At a moment t_(n), CP is made equal to 1, the optical-selector switchturns the signal X(t_(n+1)−T/2) at the logic-signal-input port 11 to thefirst intermediate-signal-output port 13, and the signal X(t_(n+1)−T/2)is further projected to the first intermediate-signal-input port 21 ofthe PhC-structure unit 02; and simultaneously, the optical-selectorswitch turns the reference-light E at the reference-light-input port 12to the second intermediate-signal-output port 14, and thereference-light E is further projected to the secondintermediate-signal-input port 22 of the PhC-structure unit 02; theoutput at the port 24 at this moment can be obtained from the expression(2):Q ^(n+1) =X(t _(n+1) −T/2)+X(t _(n) −T/2)=X(t _(n+1))+X(t _(n))  (7)

The output at the output port 24 of the PhC-structure unit 02 is equalto the input at the D-signal-input port 52 of the DFF 05, and it can beobtained from the expressions (6) and (7) that the input signal at theD-signal-input port 52 is X(t_(n)−T/2) for CP=0 and isX(t_(n+1))+X(t_(n)) for CP=1.

It can be known according to the logic characteristic of the DFF thatfor CP=1, the system output follows the input signal D; and for CP=0,the system output keeps the input signal D of the previous moment. Thus,it can be known that the output Q^(n+1) at the system output port 53 ofthe device in the present invention is Q^(n+1)=X(t_(n+1))+X(t_(n)) forCP=1; and at a next moment for CP=0, the system output keeps the outputof the previous moment, i.e., the system output in a clock period is:Q ^(n+1) =X(t _(n+1))+X(t _(n))  (8)

Hence, the device in the present invention can realize theself-OR-transformation logic function of logic-signals. If the delayeris changed into a T/2-step memory, the same function can be realized.

For the operating wavelength of 2.976 μm in the device, and the latticeconstant d of 1 μm for the PhC-structure unit 02, the radius of thecircular high-refractive-index linear-dielectric pillar 25 is 0.18 μm;the long sides of the first rectangular high-refractive-indexlinear-dielectric pillar 26 are 0.613 μm, and the short sides are 0.162μm; the size of the second rectangular high-refractive-indexlinear-dielectric pillar 27 is the same as that of the first rectangularhigh-refractive-index linear-dielectric pillar 26; the side length ofthe central square nonlinear-dielectric pillar 28 is 1.5 μm, and thethird-order nonlinear coefficient is 1.33×10⁻² μm²/V²; and the distancebetween every two adjacent rectangular linear-dielectric pillars is0.2668 μm. Based on the above dimensional parameters, for the logicsignal X(t−T/2) is input according to the waveform shown in FIG. 3, asystem output waveform diagram at the lower part of this figure can beobtained under the control of the clock-signal CP. Hence, the systemcarries out OR-logic operation on the logic input quantity X(t_(n+1))and the logic input quantity X(t_(n)) of the previous moment. That is,the self-OR-transformation logic function of logic-signals is realized.

With reference to FIG. 3, the device in the present invention canrealize the same logic function under different lattice constants andcorresponding operating wave lengths by scaling.

To sum up, the self-OR logic function of all-optical-logic-signals inthe present invention can be realized through cooperation of aPhC-structure unit with a 2×2 optical-selector switch, a delayer ormemory, a reference-light source and a DFF.

In the logic-signal processing in an integrated optical circuit,self-convolution operation of a single logic signal can be defined, andthe above-mentioned self-OR logic operation of logic-signals is a basicoperation of the self-convolution operation of logic-signals. Theself-OR-transformation logic function of logic-signals realized in thepresent invention plays an important role in realizing self-correlationtransformation or self-convolution operation of logic variables.

While the invention has been described in terms of various specificembodiments, those skilled in the art will recognize that the inventioncan be practiced with modification within the spirit and scope of theclaims.

What is claimed is:
 1. A photonic crystal (PhC) all-opticalself-OR-transformation logic gate, comprising: an optical switch unit(OSU), a PhC-structure unit, a reference-light source, a memory or adelayer and a D-type flip-flop (DFF); an input port of the delayer isconnected with a logic signal (X) of the OSU, and an output port of saiddelayer is connected with a X-input port of the OSU; a reference light(E) of the OSU is connected with a E-input port of said OSU; twointermediate-signal-output ports of said OSU are respectively connectedwith two intermediate-signal-input ports of said PhC-structure unit; aclock-signal (CP) is connected with a first CP-input port of said OSUand a second CP-input port of said DFF; and a signal-output port of saidPhC-structure unit is connected with a D-signal-input port of said DFF.2. The PhC all-optical self-OR transformation logic gate according toclaim 1, wherein said OSU is a 2×2 optical-selector switch.
 3. The PhCall-optical self-OR-transformation logic gate according to claim 1,wherein said PhC-structure unit is a two-dimensional (2D) PhCcross-waveguide nonlinear cavity; said PhC-structure unit is the 2D-PhCcross-waveguide four-port network formed by high-refractive-indexlinear-dielectric pillars, a left port of the four-port network is afirst intermediate-signal-input port, a lower port is a secondintermediate-signal-input port, an upper port is a signal-output port,and a right port is an idle port; two mutually-orthogonalquasi-one-dimensional (quasi-1D) PhC structures are placed alonglongitudinal direction in vertical waveguide and transverse direction inhorizontal waveguide at a center of a cross waveguide; anonlinear-dielectric pillar is arranged in a middle of the crosswaveguide, the nonlinear-dielectric pillar is a nonlinear material, across section of the nonlinear-dielectric pillar is square, polygonal,circular, or oval; a dielectric constant of rectangularhigh-refractive-index linear-dielectric pillars clinging to thenonlinear-dielectric pillar and close to the signal-output port of thePhC-structure unit is equal to that of the nonlinear-dielectric pillarunder weak light conditions; and said quasi-1D PhC structures and thenonlinear-dielectric pillar constitute a waveguide defect cavity.
 4. ThePhC all-optical self-OR-transformation logic gate according to claim 1,wherein said memory or the delayer includes an input port and an outputport; an output signal of said delayer has T/2delay relative to an inputsignal thereof, where T is a clock period.
 5. The PhC all-opticalself-OR-transformation logic gate according to claim 1, wherein thememory or the delayer provides a delay of T/2.
 6. The PhC all-opticalself-OR-transformation logic gate according to claim 1, wherein said DFFincludes a clock-signal-input port, a D-signal-input port and asystem-output port; and an input signal of the D-signal-input port ofsaid DFF is equal to an output signal at the signal-output port of saidPhC-structure unit.
 7. The PhC all-optical self-OR-transformation logicgate according to claim 3, wherein said PhC structure is a (2k+1)×(2k+1)array structure, where k is an integer more than or equal to
 3. 8. ThePhC all-optical self-OR-transformation logic gate according to claim 3,wherein a cross section of the high-refractive-index linear-dielectricpillar in the 2D PhC is circular, oval, triangular, or polygonal.
 9. ThePhC all-optical self-OR-transformation logic gate according to claim 3,wherein a background filling material for the 2D PhC is alow-refractive-index dielectric having a refractive index less than 1.4.10. The PhC all-optical self-OR-transformation logic gate according toclaim 3, wherein a background filling material for the 2D PhC is air.11. The PhC all-optical self-OR-transformation logic gate according toclaim 3, wherein a cross section of the high-refractive-indexlinear-dielectric pillar of the cross waveguide is rectangular,polygonal, circular, or oval.
 12. The PhC all-opticalself-OR-transformation logic gate according to claim 3, whereinhigh-refractive-index linear-dielectric pillar of the cross waveguidehas a refractive index of value more than
 2. 13. The PhC all-opticalself-OR-transformation logic gate according to claim 3, whereinhigh-refractive-index linear-dielectric pillar of the cross waveguidehas a refractive index of 3.4.